Usage with Source

VTF support

RGB of transparent pixels

Note:Newer versions of GIMP no longer have this problem and fully support RGB transparent pixels.

GIMP's developers consider the alpha channel to represent transparency, and are not interested in supporting other uses of it. This means that GIMP is quite happy to destroy or ignore RGB color data in pixels with 0% alpha, creating horrendous problems in most 3D engines:

When the alpha channel is not being used for transparency, visible image data is replaced by jagged-edged areas of pure black

When alpha is transparency, semi-black borders appear around the edges of materials with sharp edges (a result of realtime GPU filtering)

Fortunately, so long as Layer masks are used the only operation known to trigger the problem in current versions of GIMP (future releases may be different!) is "Merge Layers". As a workaround, consider using "New from Visible" instead.